Method and apparatus for compression compatible video fingerprinting

ABSTRACT

Fingerprinting and fingerprint detection, techniques are described which, unlike typical fingerprint systems used to conceal video signals, are compatible with all conceivable forms of signal compression systems while still allowing viewing of the video signal. The fingerprint technique is based on the principle of applying very slight local spatial distortion to the pixels in a video image, and the like, by means of selected warp patterns. Thus the technique provides means for conveying, within the video signal, selected information in the form of the fingerprint which is detectable electronically but which is not noticeable to a critical viewer who is watching the video signal. That is, the resultant fingerprinted video signal will appear to be identical to the undistorted video signal. the fingerprint detection technique provides for the recovery of the conveyed information which may comprise an instruction to prevent the fingerprinted video image from being copied, messages which allow identifying the source and date of an unauthorized copy of the video image, etc.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. Pat. No. 5,659,613 ('613) issuedAug. 1997 entitled Method and Apparatus for Copy Protection for VariousRecording Media Using a Video Finger Print, by John O. Ryan and GregoryC. Copeland, to U.S. Pat. No. 5,513,260 ('260) issued Apr. 30, 1996entitled Method and Apparatus for Copy Protection for Various RecordingMedia, by John O. Ryan, and to U.S. Pat. No. 5,739,864 ('864) issuedApr. 14, 1998, entitled A Video Finger Print Method and Apparatus, byGregory C. Copeland. This application also is related to copendingpatent application Ser. No. 09/171,856, filed May 29, 1997; entitledMethod and Apparatus for Compression Compatible Video Scrambling, byJohn O. Ryan.

BACKGROUND OF THE INVENTION

There are two prior patent applications of mention above which discussvideo fingerprint methods for video signals. The '864 application by G.C. Copeland discloses a video fingerprint method that inserts a lowfrequency low level signal within the video signal, such that is notobservable to the viewer, but is readily detectable by a specialdetection circuit. This low level signal operates over many fields in amanner that makes it possible to detect and identify the source of thesignal. The disadvantage of '864 prior art is that the fingerprintmethod may not be compatible with certain video compression systems. The'613 application by J. O. Ryan and G. C. Copeland uses the concepts ofthe '260 patent application for a scrambling system for variousrecording media.

EPO Application 0 690 595 describes a method and apparatus that encodesidentification information into a stream of digital data representing anobject. The digital data representing an object is modified to addembedded identification information into the data. This modification isdone such that the resultant changes to the object are not objectionableto the user. By comparing the original data to the modified data, thepossessor of the original data can recover the embedded identificationinformation. However the identification information is effectivelyunavailable to anyone not possessing the original data.

There is a need for a secure video fingerprint method having theproperty that the fingerprinted video be compatible with the variousvideo compression systems currently in use. In particular, it should becompatible with compression systems based on for example the DiscreteCosine Transform (DCT), which may employ inter-field redundance coding.Motion picture experts group (MPEG-1 and MPEG-2) are examples of suchcompression systems. In anticipated applications, the video signalgenerally is subjected to the processes of fingerprinting, compression,decompression and fingerprint detection—in that order. The fingerprintedvideo therefore will be subjected to the processes of compression anddecompression prior to fingerprint detection.

The fingerprint systems of previous mention may tend to disturb theinter-field redundancy in a television signal that the compressionsystems of previous mention depend upon for proper operation. When theinter-field redundancy is disturbed, the bit rate requirements for thecompression system rise, possibly to an unacceptable level, for thetransmission path of the compressed video signal. Therefore there isneed for a fingerprint system that does not degrade the inter-fieldredundancy to a level that requires excessive bit rates to provide agiven picture quality.

SUMMARY OF THE INVENTION

The present invention provides a fingerprint method and apparatus whichovercomes the compression system incompatibility of the prior artfingerprint systems of previous mention, while further meeting othervarious desirable requirements such as not being observable to a viewerwhile conveying information in the active video signal.

In addition, the present invention meets requirements such as thefollowing:

Video Standards

The fingerprint method and apparatus of the invention is applicable toeither analog (NTSC, PAL, SECAM) or digital (CCIR-601) video signals.

Security

The present fingerprint method and apparatus intrinsically provides ahigh level of resistance to hacking. In other words, it is verydifficult to remove the fingerprint from the video.

Invisibility

The present fingerprint method and apparatus primarily is intended toconvey information in entertainment applications such as video movies,television (TV) shows, and the like. It is essential that thefingerprint method not affect the entertainment value of the video imagewhile being securely concealed within the image, but must be readilydetectable by, for example, a detection circuit in a disk or taperecorder or other signal processing apparatus.

General Video System Compatibility

In addition to the foregoing requirements and attendant advantages, formaximum operational flexibility, the invention ensures that thefingerprinted video signal appears as a normal video signal to most ifnot all video processing methods and devices designed to operate withunfingerprinted video signals, and the like.

In particular, the video signal's fingerprinted in accordance with theinvention is compatible with all video recording, transmitting andprocessing devices likely to exist in a production or editingenvironment. Passage of the fingerprinted video through these devicesdoes not cause the fingerprint to be removed or be made more difficultto detect.

Further, the present fingerprint method and apparatus, or at least aparticular embodiment thereof, is compatible with consumer videocassette recorders (VCRs). That is, the invention makes it possible torecord the fingerprinted video signal on a consumer grade VCR, andreplay it later for detection without any likelihood of it being removedduring the record/replay process.

More particularly, the invention provides a library of warp patterns,each of which is capable of imparting a selected degree of local spatialdistortion to a video image. In response to an operator's selection, apattern select code determines which stored warp pattern is supplied asa fingerprint signal to a warp engine. The warp engine in turn appliesthe selected warp pattern to the video image to correspondingly locallyspatially distort the image. The slight distortion imparted by theselected warp pattern is not observable to a viewer, but is detectableby a circuit in a recording device to, for example, prevent therecording device from copying the video signal. Alternatively, thefingerprint also allows subsequently comparing the originalunfingerprinted video signal and an unauthorized copy of thefingerprinted video signal, to determine the origin, date, etc., of theunauthorized copy. For example, in the event a fingerprinted videosignal is illegally recorded onto a disk or tape, the spatial distortionimparted by the fingerprint technique remains with the recorded videoimage. Thus a subsequent comparison between the pixel positions of afingerprinted signal (that is, an illegal copy) and the unfingerprintedoriginal signal, can be used to identify the source of the illegal copy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of an image in which a fingerprint has not beenapplied by the invention;

FIG. 2 is a photograph of an image in which a fingerprint has beenapplied in accordance with the invention;

FIG. 3 is a block diagram illustrating an embodiment of a fingerprintapparatus in accordance with the invention; and

FIG. 4 is a block diagram illustrating an embodiment of a fingerprintdetection apparatus in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and apparatus forfingerprinting, via a signal fingerprinting technique, various programdistribution media such as digital video disk (DVD) or digital videocassette recorder (DVCR), as well as broadcast and cable videodistribution channels.

A compression system such as, for example, MPEG 1 and 2 of previousmention, relies on the condition that a high degree of redundancy existsin the image, both intra-field and inter-field redundancy.

The invention employs the same basic spatial image distortion concept asdisclosed in the above-mentioned related application entitled Method andApparatus for Compression Compatible Video Scrambling, by J. O. Ryan.However, the present invention applies a much smaller distortion whichcan still be detected by a suitable circuit and which will not benoticeable to a viewer.

The explanation of the invention method and apparatus is facilitated bythe following analogy. Consider a scene viewed through a sheet ofcolorless transparent glass with a slightly bumpy surface. By specifyingvery slight“bumpiness” parameters, the resultant image will appear to beidentical to the undistorted image, although the positions of thespecific pixels in the image are slightly shifted relative to theirnormal positions. In effect, the applied fingerprint does not distortthe image visibly, but the small distortion may still be readilydetectable by a suitable detector circuit. For example, a recorderhaving this fingerprint detector circuit could be prevented from copyingthe fingerprinted video signal. Thus, in effect the fingerprint added tothe video signal is a means for conveying a message or instructionwhich, in the above example, instructs the recorder to not copy thevideo signal. Alternatively, in the event that an illegal copy of thefingerprinted video signal is found, the message conveyed can be used toidentify the source of the illicit copy, the date of recording, or otherinformation.

Although the present invention conveys information within the videosignal, the fingerprint technique is compatible with all conceivableforms of compression systems because the application of the fingerprintdoes not materially increase the information content of the videosignal. The various pixels may be very slightly closer or further fromeach other in any direction. Thus it follows that the high frequencycontent or detail is very slightly increased and decreased in variousareas of the image, but there is no noticeable change in the bit rate ofthe compressed (or uncompressed) signal.

Thus, the technique of the invention is based upon a“local spatialdistortion” of the active video signal. More particularly, the inventioncomprises a particular kind of optical image scrambling which whenmodeled in the video domain becomes the basis of a video fingerprintsystem having all of the desirable properties and requirements, and thusthe attendant advantages, of previous mention.

To this end, a video processing means for providing the fingerprintmethod and apparatus of the invention, embodies a slight local spatialimage distortion of a video signal which is not visually noticeable andwhich is electronically detectable. Such a device is referred to hereinas a spatial image distortion (SID) fingerprint inserter having thefollowing properties:

displacement of each pixel of the original image by a slight amountunnoticeable to the eye (which may be zero) horizontally and/orvertically.

maintaining a given pixel in the fingerprinted image with the same setof contiguous pixels that it had in the original image.

An array of number pairs, one pair for each pixel, is needed to describethe fingerprint signal for each field. The field fingerprint signal,herein termed a“warp” pattern for ease of description, may be arrangedto remain fixed for relativity long periods, to change slowly with time,or to change from field to field. By appropriate choice of warp patternsand by limitation of their range so as to be detectable electronicallybut not visually noticeable, it is possible to effect a fingerprintsystem having all of the properties and requirements specified above.

There are an infinite number of warp patterns available each of whichdesignates the amount of displacement horizontally and vertically ofeach pixel in the image. The warp pattern can be fixed for an entiremovie or vary throughout the movie.

In one application of the invention the warp pattern remains unchangedthroughout the entire movie or program, and that particular pattern maydesignate a particular copy, or the broadcast time and source, of theprogram for broadcast application. If illicit copies of the program arediscovered later, these copies may be compared with the originalunwarped program in a suitable correlating device which identifies thespecific warp pattern used, to thereby identify the source of theillicit copy.

For this application, the warp pattern can be“morphed” from one patternto another, or can be faded to zero warp and back again, preferablygradually over a selected time interval such as a number of frames up toa longer time interval of a plurality of seconds. The purpose forapplying changing warp patterns is to increase the level of security,that is, to make it even more difficult for unauthorized persons todiscover the identify of the warp pattern and thus override thefingerprint process.

In another application the teachings of the present invention may beused to convey FIG. 3 illustrates an embodiment of a fingerprintapparatus of the invention herein referred to as a fingerprint inserter10. A digital video signal or the like is supplied to a field/framestore 14 via an input lead 12. The field/frame store 14 provides meansto store a field or frame of video and to supply the video to a firstinput of a warp engine 16. In response to a user selection, a warppattern select code generator 18 generates a warp pattern select codewhich, in turn, selects a desired warp pattern from a warp patternlibrary 20 which may include for example a look up table. The selectedwarp pattern is supplied as a fingerprint signal to a second input ofthe warp engine 16. The warp pattern is applied by the warp engine todistort accordingly the pixel positions in the appropriate lines of thefield or frame of video from the field/frame store 14. The output of thewrap engine 16 consists of the fingerprinted video signal which issupplied to a pattern select code inserter circuit 22. Circuit 22inserts a code identifying the selected pattern into the fingerprintedvideo signal, which then is coupled via an output lead 24 to anydownstream digital processing circuits and/or devices used in theassociated video processing application.

For example, a particular SID pattern may be used which generates aslight vertical nonlinearity in the scene, such that while the center ofthe image is held fixed, the top and bottom regions are caused tomeander vertically about their proper locations at a predetermined rate.The amount of the displacement may be a fraction of a percent of pictureheight so as to be invisible, and the rate of change may be, say, onecycle per second. instructions to a device such as, for example, a videorecording device.

FIG. 3 illustrates an embodiment of a fingerprint apparatus of theinvention herein referred to as a fingerprint inserter 10. A digitalvideo signal or the like is supplied to a field/frame store 14 via aninput lead 12. The field/frame store 14 provides means to store a fieldor frame of video and to supply the video to a first input of a warpengine 16. In response to a user selection, a warp pattern select codegenerator 18 generates a warp pattern select code which, in turn,selects a desired warp pattern from a warp pattern library 20 which mayinclude for example a look up table. The selected warp pattern issupplied as a fingerprint signal to a second input of the warp engine16. The warp pattern is applied by the warp engine to distortaccordingly the pixel positions in the appropriate lines of the field orframe of video from the field/frame store 14. For example, a particularSID pattern may be used which generates a slight vertical monlinearityin the scene, such that while the ccenter of the image is held fixed,the top and bottom regions are caused to meander vertically about theirproper locations at a predetermined rete. The amount of the displacementmay by a fraction a percent of picture height so as to be invisible, andthe rate of change may be, say, one cycle per second.

FIGS. 1 and 2 illustrate an original picture or video image without afingerprint and a video image with the addition of a fingerprint,respectively, in accordance with the present invention. As may be seenin FIG. 2, the application of a warp pattern does not cause a visuallynoticeable distortion in the image.

A suitable detector may be constructed as shown in FIG. 4. Firstly, inorder to minimize the effect of normal scene movements, a motiondetector 30 examines the edges and the center region of the image formovement and applies a compensating correction via a motion corrector 32to the video, which then is fed to a SID detector 34. In the event thatlarge changes are detected, the measurement process is temporarilyhalted. This makes it easier for the SID detector to detect the SIDpattern in the presence of normal scene motion. The motion-compensatedvideo is thus subjected to motion detection in only those regionsaffected by the SID pattern, in this case regions near the top andbottom of the image. The resulting motion vectors are examined in acomparator 36 for correspondence both in magnitude and time withreference vectors expected for the particular SID pattern used, and if acorrespondence is found the “fingerprint” has been detected.

For example, a particular SID pattern may be used which generates aslight vertical nonlinearity in the scene, such that while the center ofthe image is held fixed, the top and bottom regions are caused tomeander vertically about their proper locations at a predetermined rate.The amount of the displacement may be a fraction of a percent of pictureheight so as to be invisible, and the rate of change may be, say, onecycle per second.

A suitable detector may be constructed as shown in FIG. 4. Firstly, inorder to minimize the effect of normal scene movements, a motiondetector examines the edges and the center region of the image formovement and applies a compensating correction to the video fed to theSID detector. In the event that large changes are detected, themeasurement process is temporarily halted. This makes it easier for theSID detector to detect the SID pattern in the presence of normal scenemotion. The motion-compensated video is then subjected to motiondetection in only those regions affected by the SID pattern, in thiscase regions near the top and bottom of the image. The resulting motionvectors are examined for correspondence both in magnitude and time withthe vectors expected for the particular SID pattern used, and if acorrespondence is found the “fingerprint” has been detected.

In one this embodiment, the fact that the video has undergone spatialimage distortion according to some pre-arranged pattern and/or timetableis used to indicate the source of an illicit copy. The various sourcesor prints of the original video are subjected to different SID patternswhich uniquely identify the source or the print. At a later time, if anillicit copy of the program surfaces, it will be possible to identifythe source or print from which this copy was made.

To do this, the original video (from an archive) is compared with theillicit copy. The two video signals are first frame-synchronized and thesignal levels are adjusted to be equal. Any horizontal or verticaloffsets between the two images are also corrected for using simplesubtraction techniques to show up difference.

In one embodiment of the invention, the SID may be applied only tospecific segments of the video program. In another embodiment, aspecific SID pattern may be faded in and out according to a specifictimetable. Or both embodiments may be combined to increase the possiblepermutations. In an example of the latter, a particular SID pattern maybe used which generates a slight horizontal non-linearity in the scene,such that while both sides of the image remain fixed, the centermeanders to the left and right of its proper location at a predeterminedrate. Furthermore, only certain time segments of the program aresubjected to this distortion. An operator viewing the subtracted imageson a monitor can easily see this SID pattern, note the time segmentswhen it occurs and its rate of change, and thereby identify the sourceof the illicit copy. Although the invention has been described hereinrelative to specific embodiments, various additional features andadvantages will be apparent from the description and drawings. Forexample, the invention techniques may be applied to a medium other thanvideo signals, such as, for example, photographs, computer generatedimages, etc. By way of example, the local spatial distortion techniquecan be used to identify the origin of illegal copies of proprietaryphotographs. To this end, as described above, a negative of a photographmay be electronically reproduced several times using a slightlydifferent warp pattern each time by altering the scanning beam veryslightly. Each resulting new negative thus contains a different fixedspatial distortion which can be detected subsequently in accordance withthe invention as described above to identify the photograph and thus thesource of any illegal copies thereof.

Thus the scope of the invention is defined by the following claims andtheir equivalents.

What is claimed is:
 1. A method of conveying specific information in avideo image and the like, without visually degrading the video imagescomprising the steps of: providing a predetermined warp patterncommensurate with a selected very slight local spatial distortion to beapplied to the video image; applying the selected very slight localspatial distortion to the video image to locally very slightly displaceselected portions of the image with respect to their normal locations byan amount that is unnoticeable to a viewer but which represents thespecific information, in response to the warp pattern; wherein thepattern of said very slight local spatial distortion is compatible withsignal compression processes; and detecting the specific informationconveyed in the video image by comparing the selected very slight localspatial distortion in the conveyed video image with the undistortedoriginal video image to recover the specific information such as theoriginating source, the date of the image and/or whether the image isnot to be copied.
 2. The method of claim 1 including the step of:storing a multiplicity of predetermined warp patterns each commensuratewith selected different patterns of very slight local spatialdistortions, wherein each pattern represents the specific informationsuch as the different originating source, date of the image and/orwhether the image is to be copied, said different patterns to be appliedto video fields of respective versions of the video image.
 3. The methodof claim 2 wherein the selected portions correspond to pixels, and thedifferent warp patterns of the very slight local spatial distortionsapplied to the pixels of the video image renders the conveyed videoimage watchable while being electronically detectable.
 4. The method ofclaim 3 including the step of: retaining information which identitiesthe predetermined warp pattern and thus the specific very slight localspatial distortion used, to allow subsequent identification of a copy ofthe conveyed video image.
 5. The method of claim 2 wherein there are asuccessive plurality of changing video images over a period of time,wherein a fixed warp pattern is applied to the plurality of images overthe period of time.
 6. The method of claim 2 wherein there are asuccessive plurality of changing video images over a period of time,wherein changing warp patterns are applied to the plurality of imagesover the period of time.
 7. The method of claim 6 wherein the warppatterns change slowly over a time period of from a field to severalseconds of time.
 8. The method of claim 2 including the steps of:applying a different warp pattern to each version of the video image toprovide each version with different specific information whichidentifies the thusly fingerprinted video image; detecting the differentspecific information in each of the respective fingerprinted versions;and comparing the different detected specific information of respectivefingerprinted versions of the video image with the unfingerprintedoriginal video image to identify an illicit copy of the video image. 9.The method of claim 1 including: supplying the original video image inthe form of a two-dimensional array of pixels; and wherein the step ofapplying includes locally spatially displacing very slightly the pixelswithin the array while retaining inter-pixel relationships, in responseto a predetermined warp pattern, to provide a fingerprinted video imagein which the specific information is conveyed.
 10. The method of claim 9wherein the step of applying further includes the steps of: displacingeach pixel of the video image by the selected very slight amount,beginning with zero amount, horizontally and/or vertically to representthe specific information to be conveyed; and maintaining thecompatibility with signal compression processes by maintaining a givenpixel in the displaced pixels within the same set of contiguous pixelsthat it had in the original video image.
 11. The method of claim 10wherein the pixels are displaced a selected fraction of a pixel.
 12. Themethod of claim 9 wherein the fingerprinted video image is delivered viaa delivery networks, including the steps of: detecting the pixel spatialdisplacements between the undistorted original video image and anillicit copy of the delivered fingerprinted video image; and wherein thedisplacements correspond to the fingerprint and comprise the specificinformation conveyed with the video image.
 13. The method of claim 12including the step of: comparing the pixel spatial displacements with amultiplicity of the predetermined different warp patterns to determinethe warp pattern corresponding to the fingerprint contained in theillicit copy, to identify the originating source and/or the date of theillicit copy.
 14. The method of claim 9 wherein the fingerprinted videoimage is delivered as a succession of video fields containing thespecific information, including the steps of: detecting the fingerprintin the video image by detecting the very slight local pixeldisplacements in the fields of video; and preventing the deliveredfingerprinted video image from being copied in response to the step ofdetecting the fingerprint.
 15. Apparatus for conveying specificinformation in video data and the like, without visually degrading thevideo data, comprising: means for generating a warp pattern select codecommensurate with a selected very slight local spatial distortion to beapplied to the video data; means responsive to the warp pattern selectcode for applying a corresponding selected warp pattern to the videodata to effect the selected very slight local spatial distortion asspecific very slight local spatial displacements of portions of thevideo data from their normal locations; and a receiving facility fordetecting the specific information conveyed in the video data bycomparing the specific very slight local spatial displacements with theundistorted original video data.
 16. The apparatus of claim 15 whereinthe data comprises fields of video, and the means for applying includes:memory means for storing a plurality of selected warp patterns; meansresponsive to the memory means for applying a specific warp pattern toone or more fields; and wherein the selected warp patterns each providea different very slight local spatial distortion indicative of aconveyed specific information, which distortion is unnoticeable in thevideo data while being detectable electronically.
 17. The apparatus ofclaim 16 wherein each of the very slight local spatial distortionsapplied by the respective warp patterns comprises a fingerprint whichrepresents the specific information conveyed within the video dataitself, and wherein the fingerprints are compatible with signalcompression processes.
 18. The apparatus of claim 17 wherein thefingerprinted video data is selectively delivered to the receivingfacility, including: means receiving the fingerprinted video data forpreventing the copying of the video data in response to the specificinformation conveyed via the fingerprint in the video data.
 19. Theapparatus of claim 15 including: a field/frame store for storing andproviding fields or frames of the video data, wherein a field or framecomprises a two-dimensional array of pixels; memory means comprising awarp pattern library for storing a multiplicity of warp patterns each ofwhich imparts a different pattern of distortion representing a specificinformation to said array of pixels; and said generating means suppliesto said applying means a selected warp pattern commensurate with arespective fingerprint, from the multiplicity of warp patterns stored inthe warp pattern library.
 20. The apparatus of claim 19 wherein saidgenerating means supplies to the applying means a selected succession ofchanging warp patterns over a predetermined period of time.
 21. Theapparatus of claim 19 wherein the applying means includes: a warp enginereceiving said array of pixels and responsive to said selected warppattern for displacing the pixels of the array by selected very slightlocal spatial amounts while maintaining each pixel in the displacedpixels within the same set of pixels originally contiguous therewith tomaintain the compression process compatibility.
 22. The apparatus ofclaim 15 wherein the video data comprises a two-dimensional array ofpixels and contains a fingerprint corresponding to the specificinformation being conveyed, and is selectively delivered to thereceiving facility which includes: means for detecting the spatialplacements of the pixels in the original video data versus thecorresponding very slight local spatial displacements of the pixels inan illicit copy of the fingerprinted video data; and means for comparingthe pixel displacements with a plurality of warp patterns to determinethe identity of the corresponding fingerprint and thus of the illicitcopy.
 23. Apparatus for conveying specific information in video data byfingerprinting the video data and the like, comprising: a field/framestore for providing a field or frame of the video data; a code generatorfor generating a warp pattern select code; a memory for supplying aselected warp pattern corresponding to the specific informationcontained in a respective fingerprint in response to the warp patternselect code; a circuit for applying the fingerprint to the field orframe of video data by locally slightly displacing individual portionsof the field or frame from their normal locations in response to theselected warp pattern, wherein the fingerprint is not noticeable to aviewer but is detectable electronically; wherein the pattern of thefingerprint is compatible with signal compression processes; and meansfor delivering the fingerprinted video data to a receiving facility,said fingerprint conveying to the receiving facility the specificinformation pertinent to the field or frame of video data.
 24. Theapparatus of claim 23 wherein: the memory means includes a lookup tableof a multiplicity of warp patterns each of which imparts a differentpattern of distortion representing a different specific information; andthe circuit includes a warp engine for locally slightly displacing theindividual portions in accordance with the respective selected warppattern.
 25. The apparatus or claim 23, including: means integral withthe receiving means for detecting the fingerprint in the field or frameof video data; and means responsive to the detecting means forpreventing copying of the fingerprinted video data.
 26. The apparatus ofclaim 23, including: means for detecting the local slight spatialdisplacements in the individual portions of an illicit copy of thefingerprinted field or frame relative to the unfingerprinted field orframe of the original video data; and means responsive to the detectingmeans for comparing the local slight spatial displacements with amultiplicity of warp patterns to identify the specific warp pattern usedand thus identify the illicit copy of the video data.
 27. A method ofconveying specific information in selected data such as video data,computer generated data and/or photographs, by the insertion of afingerprint in the selected data, comprising the steps of: supplying arepresentation of said selected data; storing a selected plurality ofwarp patterns commensurate with different very slight local spatialdistortions representative of a respective plurality of fingerprints;selecting a warp pattern which identifies the specific information to beconveyed from said stored plurality of warp patterns; locally slightlyspatially displacing individual portions of said representation of saidselected data from their normal locations in response to said selectedwarp pattern to embed the corresponding fingerprint specific informationwithin the selected data without degrading the watchability of theselected data; and detecting the fingerprint specific information in theconveyed selected data to recover the specific information insertedtherein.
 28. The method of claim 27 wherein the fingerprinted selecteddata is selectively delivered to a receiving facility, including thesteps of: detecting the fingerprint specific information by comparingthe locally slightly spatially displaced individual portions with thenormal locations in the original selected data; and preventing thecopying of the fingerprinted selected data in response to the detectedfingerprint specific information embedded within the selected data. 29.The method of claim 27 wherein the fingerprinted selected data isselectively delivered to a receiving facility, including the steps of:detecting the slight spatial displacement in the representation of anillicit copy of the fingerprinted selected data relative to therepresentation of the corresponding unfingerprinted original selecteddata; and comparing the slight spatial displacement with the pluralityof warp patterns to determine the identity of the correspondingfingerprint specific information and thus of the illicit copy of theselected data.
 30. A method of conveying information in selected data byfingerprinting the selected data, wherein the selected data may includeanalog or digital video data, computer generated data and/orphotographs, comprising the steps of: supplying a representation of saidselected data to a first input of a warp engine; storing a selectedplurality of warp patterns, commensurate with a respective plurality offingerprints, in a warp pattern library, wherein each warp patternrepresents a different piece of information being conveyed with arespective representation; generating a pattern select code indicativeof a specific warp pattern to be applied to the selected data: selectingthe specific warp pattern from said stored plurality of patterns in thelibrary in response to the pattern select code; supplying said selectedspecific warp pattern to a second input of said warp engine to locallyvery slightly spatially displace selected portions of saidrepresentation an amount which is insufficient to be noticeable to aviewer, wherein said fingerprint conveys the different piece ofinformation within the selected data which is electronically detectablealthough not noticeable to the viewer, wherein the very slight spatialdisplacements are compatible with signal compression processes;detecting the fingerprint in the respective representation of theselected data; and determining the different piece of informationrepresented by the detected fingerprint.
 31. The method of claim 30including the steps of: delivering the fingerprinted selected data to areceiving facility; wherein the steps of detecting and determininginclude comparing the very slight spatial displacements withcorresponding placements of the original representation of the selecteddata; and applying the detected piece of information to prevent copyingof the fingerprinted selected data and/or to identify a source of anunauthorized copy of the selected data.